Fluid control means for rock drill feed leg

ABSTRACT

A pneumatic drill with a fluid operated extensible feed leg having a means therein responsive to a change of pressure to provide a quick pressure release for pressurized fluid in the feed leg.

United States Patent John E. Gordon 337 Main St. E., Galt, Ontario, Canada 81 1,910

Apr. 1, 1969 June 22, 1971 lnventor Appl. No. Filed Patented FLUID CONTROL MEANS FOR ROCK DRILL FEED LEG 7 Claims, 5 Drawing Figs.

U.S.Cl. 173/36, 173/158, 173/159 Int. Cl EZlc 5/11 Field of Search 173/36, 158, 159, 1

[56] References Cited UNITED STATES PATENTS 1,845,805 2/1932 Nell 173/158 X 3,011,569 12/1961 Dick 173/158 3,085,638 4/1963 Larcen 173/36 Primary Examiner--Emest R. Purser Attorney-E. Wallace Breisch ABSTRACT: A pneumatic drill with a fluid operated extensible feed leg having a means therein responsive to a change of pressure to provide a quick pressure release for pressurized fluid in the feed leg.

PATENTEU JUN22|97| 3,5 6,114

' sum 1 OF 2 Q INVENTOR. I F '1 g. E Jofin E. Gordon.

PATENTEU JUH22 um sum 3 OF 2 Jofin Gordon FLUID CONTROL MEANS FOR ROCK DRILL FEED LEG The use of fluid activated feed leg rock drills as presently constructed requires a loss of operation time to retract the feed leg to the uncxtended position thereof because the compressed air contained within the air cylinder means must be returned to the atmosphere through passages in the drill before the retraction operation can begin.

Attempts have been made to shorten the exhaust time of the pressurized air contained within the rock drill and feed leg by enlarging the air passages and making them as short as possible, however, size and weight restrictions of the rock drill assembly limits the maximum diameters of the air passageways and because it is desirable to have the air control mechanism made convenient for the manual manipulation by the operator it is most difficult to obtain relatively short passageways.

In the preferred embodiment of this invention a pilot operated quick pressure release valve is placed at any point within the air passage to the feed cylinder to selectively communicate the passage directly with the ambient atmosphere, thereby providing means for the air pressure within the feed cylinder to return to atmospheric pressure in an optimum time.

The objects and advantages of this invention will be more readily apparent from the following description and drawings of a preferred embodiment of this invention in which:

FIG. 1 is a fragmentary side view of an illustrative pneumatically activated feed leg rock drill with an adapter embodying the pilot operated quick release valve of this invention;

FIG. 2 is a partial side elevational view taken substantially on line 2-2 of FIG. 1

FIG. 3 is a partial cross-sectional view taken substantially on line 3-3 of FIG. 1;

FIG. 4 is a cross-sectional view of the adapter with the pilot operated release valve shown therein, taken on line 4-4 of FIG. 2;

FIG. 5 is a cross-sectional view of the adapter without the release valve, taken on line 5-5 of FIG. 2.

Referring to FIG, 1, a rock dn'lling tool, generally indicated at is of the hammer type, for percussively actuating a conventional drill steel carrying a drill bit. The drilling tool, when in use, is supported, at least in part, by a pivotally connected extensible feed leg 11 which, in the present example, is of the pneumatically operated cylinder and piston type of a construction well know in the art. The usual control valve 6 for controlling the supply of air under pressure to operate the drilling tool and the feed leg is provided at the rearward end of the drill tool 10 between a fluid supply conduit 11 and the drill body 10. The control valve which has a fluid transmitting mode for supplying pressure fluid to the leg and a pressure releasing mode whereby the supply passageways are connected to atmosphere, additionally operates as a pilot valve for the pilot operated quick pressure release valve 12, of this invention as hereinafter described.

The means for pivotally connecting the drilling tool 10 to the reciprocal element of the feed leg 11 are of a construction well known in the art and comprise: a boss 14 integral with the underside of the housing of the drilling tool; a vertically elongated detachable adapter coupling member 16, which contains therein the quick release valve 12 and means for operating valve 12 of this invention as hereinafter described; a yoke assembly 18 which pivotally connects members 14 and 16; and a nut 20 for releasably securing the adapter member 16 to the feed leg 11. The lower periphery of boss 14 and the upper periphery of member 16 can be of any suitable shape which will allow a well-known rearward movement of feed leg 11.

As shown, member 16 comprises a main coupling portion 22 which has a threaded feed leg connecting portion 24 extending therefrom, illustratively downwardly, and a rearwardly extending vertically elongated ear portion 26, which contains the valve assembly 12 therein. Suitable transversely extending bores 46 and 48, preferably tapered, are, respectively, formed centrally through the boss 14 and portion 22 to receive respective pivot pin elements 47 and 49 of yoke assembly 18 therein in a manner well known in the art and illustrated in U.S. Pat. No.2,929,6l1.

Referring to FIGS. 3 through 5, the ear portion 26 contains therein an elongated three-step through bore 28 which extends slightly diagonally upward and rearward, as illustrated in FIG. 4, from the lower end thereof and comprises: a lower threaded bore portion 30 which threadably receives, as shown a standard pipe plug 32 therein, the top surface 59 of which is located intermediate the axial ends of bore portion 30; an intermediate bore portion 36 (see FIG. 5) of a lesser diameter than portion 30, which slidably receives the valve member 12 therein and has valve seating surface 37 at the upper end thereof forming a shoulder with an upper air exhaust bore portion 38 having a smaller diameter than portion 36 and communicating with the atmosphere. Intermediate bore portion 36 has an elongated communicating chamber 39 (see FIG. 2) ex tending radially forwardly at the upper end thereof.

Valve member 12 has an axial length approximately equal to the axial length of bore portion 36 and comprises: a lower cylindrical portion 40 of a diameter to be slidably received in bore 36 and an axial length greater than the axial distance from surface 59 of the inserted plug 32 to the uppermost end of bore portion 30; and an upper coaxial cylindrical portion 42 of a diameter intermediate the diameter of bore portions 36 and 38. A plurality of axially extending through passageways, as shown one passageway 44, is provided in valve portion 40 radially outwardly adjacent the outside diameter of portion 42 for a purpose hereinafter described. A lower surface 60 of the quick release valve 12 has a concentric raised portion 61 extending downwardly therefrom. Portion 61 has a relatively small diameter in relation to surface 60. When no pressure fluid is flowing or when the feed leg 11 is undergoing retraction, in a manner hereinafter described, the raised portion 61 of the quick release valve 12 is in contact with surface 59 of pipe plug 32, thereby resulting in portion 40 having a lower section thereof contained within bore portion 30 and an upper section thereof contained within bore portion 36, in a position hereinafter referred to as the retracted position" of valve member 12.

The feed leg 11 is extended by providing pressure fluid thereto through well-known connected passageways (a serial plurality of communicating passageways) from the pressurized fluid supply (not shown), through rock drill passageways 7, through boss passageways 8, through passageways 9 contained within the yoke assembly 18, through passageways contained within the adapter member 16, as hereinafter described in detail, and discharging into feed leg cylinder, where the fluid under pressure applies forces tending to extend the feed leg 11 from the retracted position thereofin a manner wcll-known in the art.

When fluid under pressure is supplied to extend the feed leg 11, the fluid is introduced into bore 48 of member 16 from a passageway 9 in the lower portion of the yoke assembly 18 in a manner well known in the art. The flow of fluid under pressure from bore 48 into the feed leg 11 is as follows: through a passageway 50 which communicates between bore 48 and an intermediate point in bore portion 30 above the plug surface 59 where the pressure fluid flowing through the clearance between valve surface 60 and plug surface 58 maintained by raised portion 61, urges valve member 12 axially upward from the retracted position" thereof, resulting in valve member 12 being fully contained within bore portion 36 in such a way that the upper end of portion 42 is in contact with seating surface 37 thereby sealing the air exhaust bore portion 38 from the atmosphere for the entire feed leg extending cycle; through a lower chamber 52 of portion 30 which is bounded by the surfaces 59 and 60; through bore 44; through an upper chamber 54 defined by the difference between the outer periphery of valve portion 42 and the inner periphery of bore portion 36; through the communicating chamber 39; and through a passageway 56 which is directed diagonally downward from the chamber 39 and open ends into the inner end of a blind bore 58 which is coaxial with and extends axially upward from the lower end of the adapter coupling portion 24. The pressure fluid discharges from bore 58 into feed leg 11 enabling leg 11 to extend to the feed position thereof. During the entire feed leg extending cycle the pressure differential between the chamber 52 and atmospheric pressure maintains the sealing contact between valve 12 and seating surface 37.

To retract the feed leg 11 from the extended position thereof the supply of pressure fluid is shut off and the passageways 7 in the rock drill 10 are opened to the atmosphere by the control valve 6 located at the rearward end of the drill tool 10. The compressed pressure fluid contained within the feed cylinder of the feed leg 1] expands: through bore 58; through passageway 56 into chamber 54 where, because of the restricted flow through passageway 44, the pressure in chamber 54 drops more slowly than in chamber 52, and the pressure differential biases the valve 12 axially downwardly to the retracted position" thereof opening the air exhaust portion 38 through which the pressure fluid rapidly exhausts because of direct communication between the air leg and the ambient atmosphere.

It is to be noted that within the scope of this invention, the bore 44 may be a single bore, as shown, a plurality of similarly located bores, as described, one or more axial notches in the periphery of valve portion 40 or even just suitably sized clearance between the valve portion 40 and the bore portion 36 to provide the return air pressure drop necessary for moving the valve 12 to the retracted position" as above described.

Thus, the method of operating a pneumatic rock drill feed leg according to the instant invention comprises the steps of supply ng compressed air to the feed leg 11 and later exhausting such compressed air from the feed leg 11, wherein during the supply step the compressed air travels through a serial plurality of communicating supply passageways 7, 8, 9, 48, 50, 52, 44, 39, 56 and 58 to and into said feed leg 11 and during the exhaust step the compressed air is liberated to the ambient air after traversing less than one-half of said plurality of passageways namely only passageways 58, 56 and 39 plus a different passageway 38. 1

Although a preferred embodiment of this invention has been described and illustrated herein one skilled in the art can readily embody the principles of this invention in other forms to obtain the same operation and advantages, for example the location of the pilot operated quick pressure release valve is not restricted to the feed leg connection adapter but can be incorporated into the leg itself or in any part of the passages connecting the control valve on the drill and the feed leg.

What I claim is:

1. In a pneumatic drill with a fluid operated extensible feed leg the extension and retraction of which is controlled by the fluid flow through a fluid supply valve cooperable with one of a serial plurality of fluid conducting passageways in a fluid conducting supply conduit, in the body member of said pneumatic drill and in feed leg, said fluid supply valve having a fluid supplying mode for providing a flow of pressurized fluid to said feed leg through said passageways and a pressure releasing mode for discontinuing said flow of pressurized fluid to said feed leg, the improvement comprising: passageway means communicating between at least one of said passageways and the ambient atmosphere; flow control valve means in said passageway means and operable in response to a change in pressure in said passageways to shut off said passageway means whenever said supply valve is operated into said fluid supply mode and to open said passageway means whenever said supply valve is operated into said pressure releasing mode.

2. A pneumatic drill as specified in claim 1 wherein said at least one of said passageways is in a top element of said feed leg.

3. A pneumatic drill as specified in claim 1 wherein said supply valve is in a handle portion of the body of said drill.

4. A pneumatic drill as specified in claim 1 wherein said control valve means in said passageway means is pilot operable to shut off said passageway means whenever the fluid pressure in said body member passageways is greater that the fluid pressure in said feed leg passageways and to open said passageway means whenever the fluid pressure in said body member passageways is less than the fluid pressurein said feed leg passageways.

5. A pneumatic drill as specified in claim 4 wherein said at least one of said passageways is within a top portion of said feed leg.

6. A pneumatic drill as specified in claim 5 wherein said pilot operated valve is held closed by a pressure differential between the interior of said at least one of said passageways and the exterior of said feed leg and said pilot operated valve is opened by rapidly reducing said pressure differential.

7. A pneumatic drill as specified in claim 1 wherein said control valve means in said passageway means is pilot operable to shut off said passageway means whenever the fluid pressure in said passageways upstream of said passageway means is greater than the fluid pressure in said passageways downstream of said passageway means and to open said passageway means whenever the fluid pressure in said passageways upstream of said passageway means is less than the fluid pressure in said passageways downstream of said passageway means. 

1. In a pneumatic drill with a fluid operated extensible feed leg the extension and retraction of which is controlled by the fluid flow through a fluid supply valve cooperable with one of a seriaL plurality of fluid conducting passageways in a fluid conducting supply conduit, in the body member of said pneumatic drill and in feed leg, said fluid supply valve having a fluid supplying mode for providing a flow of pressurized fluid to said feed leg through said passageways and a pressure releasing mode for discontinuing said flow of pressurized fluid to said feed leg, the improvement comprising: passageway means communicating between at least one of said passageways and the ambient atmosphere; flow control valve means in said passageway means and operable in response to a change in pressure in said passageways to shut off said passageway means whenever said supply valve is operated into said fluid supply mode and to open said passageway means whenever said supply valve is operated into said pressure releasing mode.
 2. A pneumatic drill as specified in claim 1 wherein said at least one of said passageways is in a top element of said feed leg.
 3. A pneumatic drill as specified in claim 1 wherein said supply valve is in a handle portion of the body of said drill.
 4. A pneumatic drill as specified in claim 1 wherein said control valve means in said passageway means is pilot operable to shut off said passageway means whenever the fluid pressure in said body member passageways is greater that the fluid pressure in said feed leg passageways and to open said passageway means whenever the fluid pressure in said body member passageways is less than the fluid pressure in said feed leg passageways.
 5. A pneumatic drill as specified in claim 4 wherein said at least one of said passageways is within a top portion of said feed leg.
 6. A pneumatic drill as specified in claim 5 wherein said pilot operated valve is held closed by a pressure differential between the interior of said at least one of said passageways and the exterior of said feed leg and said pilot operated valve is opened by rapidly reducing said pressure differential.
 7. A pneumatic drill as specified in claim 1 wherein said control valve means in said passageway means is pilot operable to shut off said passageway means whenever the fluid pressure in said passageways upstream of said passageway means is greater than the fluid pressure in said passageways downstream of said passageway means and to open said passageway means whenever the fluid pressure in said passageways upstream of said passageway means is less than the fluid pressure in said passageways downstream of said passageway means. 